Construction of high-rise buildings has been raising the need for high-speed elevators. In realizing the further speedup of an elevator, the importance of an elevator-car-vibration reduction technology has been ever increasing.
As a technology for reducing a transverse elevator-car vibration, a method exists in which a sensor for detecting a transverse car vibration and an actuator for applying vibration-damping force to the car are provided, and force, having a direction opposite to that of the transverse vibration, is applied through the actuator to the car so as to reduce the vibration (e.g., refer to Patent Document 1).
In particular, the control, in which the actuator generates force whose direction is opposite to that of a transverse car vibration and whose magnitude is in proportion to the speed of the transverse car vibration, is referred to as “skyhook damping control”. In addition, the skyhook damping control demonstrates the same effects as those demonstrated when a damping device (vibration damping device) fixed between a car and the space works; that is why it is referred to as “skyhook damping control”.
Additionally, a method also exists in which, instead of generating vibration-damping force by use of an actuator, by controlling physical parameters, of an elevator car, related to damping or rigidity, a vibration is reduced (for example, refer to Patent Document 2).
Karnopp et al. has proposed a method in which, by changing the damping coefficient of a damping device, control similar to the skyhook damper control is realized (for example, refer to Non-Patent Document 1).
When a car passes an adjacent car or a counterweight, a large wind pressure is caused, whereby the car is vibrated; thus, a method also exists in which, the speed of the car or its opponent is reduced when the car and the opponent pass each other, in order to reduce the vibration upon the mutual passing (for example, refer to Patent Document 3).
[Patent Document 1]                Japanese Patent Application Laid-Open No. 2001-122555        
[Patent Document 2]                Japanese Patent Application Laid-Open No. H09-240930        
[Patent Document 3]                Japanese Patent Application Laid-Open No. 2002-3090        
[Non-Patent Document 1]                “Semi-active Vibration Control Utilizing MR Damper” by Gongyu Pan, Hiroshi Matsuhisa, and Yoshihisa Honda, Collected Lecture Papers of the “Dynamics and Design Conference (2000), published by the Japan Society of Mechanical Engineers, September 2000.        